It's the fall of 1938, and Prime Minister Chamberlain has just signed the Munich Agreement with Adolph Hitler. An RAF officer complains about England's ongoing capitulation to Germany. After a night of drinking, he paints swastikas on Nelson's Monument. The RAF discharges him as unfit to be an officer. An acquaintance enlists him in the British secret service. He meets and courts a German woman from a prominent family. Her brother is highly placed in the Nazi propaganda works. The Germans recruit him and he gives radio broadcasts from Berlin to England, as the voice of truth. His broadcasts have a code that give the British military information. All goes well until his cover is blown and he and his German girlfriend must try to escape.